Use of potassium formate in road winter deicing can reduce groundwater deterioration

We present here an aquifer scale study on the fate of potassium formate, an alternative, weakly corrosive deicing agent in soil and subsurfaces. Potassium formate was used to deice a stretch of a highway in Finland. The fate of the formate was examined by monitoring the groundwater chemistry in the underlying aquifer of which a conceptual model was constructed. In addition, we determined aerobic and anaerobic biodegradation rates of formate at low temperatures (-2 to +6 degrees C) in soil microcosms. Our results show that the formate did not enter the saturated zone through the thin vadose zone; thus, no undesirable changes in the groundwater chemistry were observed. Furthermore, the conceptual model explained the distribution of chloride in the aquifer used in deicing for the past 30 years. We recorded mineralization potential up to 97% and up to 17% within 24 h under aerobic and anaerobic conditions, respectively, in the soil and subsurface samples obtained from the site. This demonstrates that biodegradation in the topsoil layers was responsible for the removal of the formate. We conclude that the use of potassium formate can potentially help diminish the negative impacts of road winter deicing on groundwater without jeopardizing traffic safety.